The aforementioned wheel can be a front wheel or a rear wheel of the bicycle. Such a bicycle can be a mountain-bike, a leisure bicycle or a racing bicycle.
As known, a bicycle wheel comprises a plurality of spokes extending between the hub, which constitutes the central element of the wheel intended to be associated with the frame of the bicycle, and the rim on which the tyre is mounted.
The hub comprises a substantially tubular body (hereinafter indicated as “hub body”) comprising, at each of the opposite free end portions thereof, a spoke attachment flange.
The spoke attachment flange can be made in a single piece with the hub body or can be made as a distinct piece from the hub body to then be stably associated with the hub body.
Straight-head spokes and curved-head spokes are known. In straight-head spokes the end portion for attaching to the hub extends coaxially to the longitudinal axis of the elongated body of the spoke (hereinafter also indicated as “stem”), whereas in curved-head spokes the end portion for attaching to the hub is curved, i.e. extends along a direction inclined by a predetermined angle with respect to the longitudinal axis of the stem of the spoke.
Typically, the spoke attachment flanges comprise an annular body extending coaxially to a rotation axis and comprising a plurality of seats for housing enlarged heads of the spokes.
U.S. Pat. No. 7,621,601 and US 2017/0305189 describe spoke attachment flanges with seats for housing enlarged heads of spokes. Each of these seats comprises an access hole made on a front face (anterior front face in the case of US 2017/0305189 and rear front face in the case of U.S. Pat. No. 7,621,601) of the flange to allow the insertion of the enlarged head of the spoke in the seat, and a slit made on a radially outer surface of the annular body and on the anterior front face to allow the positioning of the spoke and the subsequent tensioning thereof.
The Applicant has found that the spokes can become detensioned. Detensioning can occur for example due to the uneven road surface or due to the presence of steps or sudden obstacles.
The detensioning of the spokes can result in the accidental exit of the spokes from the respective housing seats, with the risk of damaging the hub, other spokes or other components mounted on the hub, like for example the brake disc (in the case of bicycles with a disc brake) or the sprockets mounted on the freewheel (in the case of a hub for a rear wheel), and consequent danger for the cyclist.